Assam University

About: Assam University is a education organization based out in Silchar, Assam, India. It is known for research contribution in the topics: Population & Gene. The organization has 1347 authors who have published 2649 publications receiving 27373 citations. The organization is also known as: Assam University Silchar.

Reactive oxygen species signaling in plants under abiotic stress

Abstract: Abiotic stresses like heavy metals, drought, salt, low temperature, etc are the major factors that limit crop productivity and yield These stresses are associated with production of certain deleterious chemical entities called reactive oxygen species (ROS), which include hydrogen peroxide (H₂O₂), superoxide radical (O₂(-)), hydroxyl radical (OH(-)), etc ROS are capable of inducing cellular damage by degradation of proteins, inactivation of enzymes, alterations in the gene and interfere in various pathways of metabolic importance Our understanding on ROS in response to abiotic stress is revolutionized with the advancements in plant molecular biology, where the basic understanding on chemical behavior of ROS is better understood Understanding the molecular mechanisms involved in ROS generation and its potential role during abiotic stress is important to identify means by which plant growth and metabolism can be regulated under acute stress conditions ROS mediated oxidative stress, which is the key to understand stress related toxicity have been widely studied in many plants and the results in those studies clearly revealed that oxidative stress is the main symptom of toxicity Plants have their own antioxidant defense mechanisms to encounter ROS that is of enzymic and non-enzymic nature Coordinated activities of these antioxidants regulate ROS detoxification and reduces oxidative load in plants Though ROS are always regarded to impart negative impact on plants, some reports consider them to be important in regulating key cellular functions; however, such reports in plant are limited Molecular approaches to understand ROS metabolism and signaling have opened new avenues to comprehend its critical role in abiotic stress ROS also acts as secondary messenger that signals key cellular functions like cell proliferation, apoptosis and necrosis In higher eukaryotes, ROS signaling is not fully understood In this review we summarize our understanding on ROS and its signaling behavior in plants under abiotic stress

α-Synuclein binds to TOM20 and inhibits mitochondrial protein import in Parkinson’s disease

Abstract: α-Synuclein accumulation and mitochondrial dysfunction have both been strongly implicated in the pathogenesis of Parkinson’s disease (PD), and the two appear to be related. Mitochondrial dysfunction leads to accumulation and oligomerization of α-synuclein, and increased levels of α-synuclein cause mitochondrial impairment, but the basis for this bidirectional interaction remains obscure. We now report that certain posttranslationally modified species of α-synuclein bind with high affinity to the TOM20 (translocase of the outer membrane 20) presequence receptor of the mitochondrial protein import machinery. This binding prevented the interaction of TOM20 with its co-receptor, TOM22, and impaired mitochondrial protein import. Consequently, there were deficient mitochondrial respiration, enhanced production of reactive oxygen species, and loss of mitochondrial membrane potential. Examination of postmortem brain tissue from PD patients revealed an aberrant α-synuclein–TOM20 interaction in nigrostriatal dopaminergic neurons that was associated with loss of imported mitochondrial proteins, thereby confirming this pathogenic process in the human disease. Modest knockdown of endogenous α-synuclein was sufficient to maintain mitochondrial protein import in an in vivo model of PD. Furthermore, in in vitro systems, overexpression of TOM20 or a mitochondrial targeting signal peptide had beneficial effects and preserved mitochondrial protein import. This study characterizes a pathogenic mechanism in PD, identifies toxic species of wild-type α-synuclein, and reveals potential new therapeutic strategies for neuroprotection.

Genome-wide classification and expression analysis of MYB transcription factor families in rice and Arabidopsis

Abstract: The MYB gene family comprises one of the richest groups of transcription factors in plants Plant MYB proteins are characterized by a highly conserved MYB DNA-binding domain MYB proteins are classified into four major groups namely, 1R-MYB, 2R-MYB, 3R-MYB and 4R-MYB based on the number and position of MYB repeats MYB transcription factors are involved in plant development, secondary metabolism, hormone signal transduction, disease resistance and abiotic stress tolerance A comparative analysis of MYB family genes in rice and Arabidopsis will help reveal the evolution and function of MYB genes in plants A genome-wide analysis identified at least 155 and 197 MYB genes in rice and Arabidopsis, respectively Gene structure analysis revealed that MYB family genes possess relatively more number of introns in the middle as compared with C- and N-terminal regions of the predicted genes Intronless MYB-genes are highly conserved both in rice and Arabidopsis MYB genes encoding R2R3 repeat MYB proteins retained conserved gene structure with three exons and two introns, whereas genes encoding R1R2R3 repeat containing proteins consist of six exons and five introns The splicing pattern is similar among R1R2R3 MYB genes in Arabidopsis In contrast, variation in splicing pattern was observed among R1R2R3 MYB members of rice Consensus motif analysis of 1kb upstream region (5′ to translation initiation codon) of MYB gene ORFs led to the identification of conserved and over-represented cis-motifs in both rice and Arabidopsis Real-time quantitative RT-PCR analysis showed that several members of MYBs are up-regulated by various abiotic stresses both in rice and Arabidopsis A comprehensive genome-wide analysis of chromosomal distribution, tandem repeats and phylogenetic relationship of MYB family genes in rice and Arabidopsis suggested their evolution via duplication Genome-wide comparative analysis of MYB genes and their expression analysis identified several MYBs with potential role in development and stress response of plants

A review on coronary artery disease, its risk factors, and therapeutics.

Abstract: Coronary artery disease (CAD) is one of the major cardiovascular diseases affecting the global human population. This disease has been proved to be the major cause of death in both the developed and developing countries. Lifestyle, environmental factors, and genetic factors pose as risk factors for the development of cardiovascular disease. The prevalence of risk factors among healthy individuals elucidates the probable occurrence of CAD in near future. Genome-wide association studies have suggested the association of chromosome 9p21.3 in the premature onset of CAD. The risk factors of CAD include diabetes mellitus, hypertension, smoking, hyperlipidemia, obesity, homocystinuria, and psychosocial stress. The eradication and management of CAD has been established through extensive studies and trials. Antiplatelet agents, nitrates, β-blockers, calcium antagonists, and ranolazine are some of the few therapeutic agents used for the relief of symptomatic angina associated with CAD.

Alterations in root lipid peroxidation and antioxidative responses in two rice cultivars under NaCl-salinity stress

Abstract: The comparative alterations of short term NaCl stress and recovery on growth, water relations, ionic composition, lipid peroxidation and antioxidants in roots of two rice cultivars differing in salt tolerance were studied. Exposed for 24 h to increasing (50, 100 and 150 mmol l−1) concentrations of NaCl, roots of 12D Oryza sativa L. cv. Lunishree and cv. Begunbitchi decreased in fresh weight, dry weight and relative water content. Increased Na+ and decreased K+ ion were determined at increasing NaCl concentrations. Both peroxide content and lipid peroxidation measured in terms of MDA level increased and the ratio was higher in Begunbitchi compared to Lunishree. Recovered roots showed lower peroxide and MDA content. Ascorbate and glutathione contents increased in the stressed and recovered roots of Lunishree, but decreased in Begunbitchi with increasing NaCl concentrations. Although SOD, CAT and GR activities decreased in the stressed roots, CAT activity also increased in recovered roots of both the cultivars. The POX activity increased in stressed and recovered roots of both Lunishree and Begunbitchi. Higher free radicals scavenging capacity and more efficient protection mechanism of Lunishree against salt stress, as revealed by the lower level of lipid peroxidation and improved plant water status as well as activities of some of the antioxidants, suggest that significant cultivar differences in response to salt stress in rice are closely related to differences in the activities of antioxidants and ion content. Another possible conclusion is that improved tolerance to salt stress may be accomplished by increased capacity of antioxidative system.